A Review of the 2014 AHA/ACC/HRS Guideline for the Management of Patients with Atrial Fibrillation

Introduction

The American Heart Association, American College of Cardiology, and Heart Rhythm Society have released new guidelines for the management of patients with atrial fibrillation (AF).¹ This is a complete re-write of the guidelines developed in 2006. Like all such guidelines, information from clinical trials, clinical practice, and the published literature was used to generate a consensus among the committee members. The document was made available via e-publication in March through Circulation, HeartRhythm, and the Journal of the American College of Cardiology. 

The guidelines are divided into 5 major sections: clinical characteristics and evaluation of AF; thromboembolic risk and treatment; rate control: recommendations; rhythm control; and specific groups and AF. The following is a review of the highlights and major changes seen in each section.

Clinical Characteristics and Evaluation of AF

The new clinical guidelines have changed the definitions of AF that had been stated in earlier guideline documents. The ability to make these definitional calls in recent years has been facilitated by the use of data from implanted loop recorders, pacemakers, and defibrillators.

Paroxysmal AF is defined as AF that terminates spontaneously or with a form of intervention within 7 days of onset. Subsequent episodes may recur with variable frequency. Persistent AF is continuous AF that is sustained for greater than 7 days. Longstanding persistent AF is defined as continuous AF of greater than 12 months’ duration.¹

The term permanent AF is to be used when there has been a joint decision by the patient and clinician to cease further attempts to restore and/or maintain sinus rhythm. It is stressed that this represents a therapeutic attitude on the part of the patient and clinician and does not refer to the pathophysiology of the AF. The attitude of acceptance may be subject to change with symptom evolution and availability of therapeutic options.¹

For definitional clarity within the document, nonvalvular AF is defined as AF in the absence of rheumatic mitral stenosis, a mechanical or bioprosthetic heart valve, or mitral valve repair.¹

The list of diagnostic tests/tools that may be included for the initial evaluation of the patient with AF include the following: history and physical examination; ECG; TTE; blood tests of thyroid, renal, and hepatic function; 6-min walk test; exercise testing; Holter or event monitoring; TEE; electrophysiological study; and chest radiograph.

Thromboembolic Risk and Treatment

The section on thromboembolic risk and treatment includes the therapy recommendations, a discussion of risk stratification schemes, a review of considerations in selecting anticoagulants, and a brief mention of LAA occlusion/excision.

The new guidelines have recommended the use of the CHA₂DS₂-VASc score criteria instead of the CHADS₂ score criteria to assess for stroke risk. The CHA₂DS₂-VASc incorporates a broader scoring range, including gender (women have a higher stroke rate) and vascular disease, in addition to a wider age range. Table 1 compares the CHADS₂ score criteria to the CHA₂DS₂-VASc score criteria. For patients with prior stroke, TIA, or a CHA₂DS₂-VASc score ≥2, oral anticoagulation is recommended. Dabigatran (Pradaxa, Boehringer Ingelheim), rivaroxaban (Xarelto, Janssen Pharmaceuticals), apixaban (Eliquis, Bristol-Myers Squibb/Pfizer), or warfarin can be used for those with nonvalvular AF.¹ This inclusion of the newer anticoagulants is a change from prior guidelines.

The use of these alternative anticoagulants is thought to be especially valuable in patients whose INRs with warfarin therapy are difficult to maintain in the therapeutic range. Also, the 3 newer agents have more predictable pharmacological profiles and fewer drug-drug interactions. Dietary precautions are not present as with warfarin therapy, and there is less intracranial bleeding with these agents than with warfarin.¹ However, warfarin is the only recommended therapy for those with mechanical heart valves. Dabigatran is not recommended for those with mechanical heart valves.

The discussion of cardiac surgery for LAA occlusion/excision to reduce stroke risk produced only a class IIb recommendation, that surgical excision of the LAA may be considered in patients undergoing cardiac surgery. 

Rate Control: Recommendations

The rate control recommendations state that ventricular rate should be controlled using a beta blocker or nondihydropyridine calcium channel antagonist for paroxysmal, persistent, or permanent AF, and that heart rate control during exertion should be assessed, adjusting pharmacological therapy as necessary.¹ A list of recommended rate control medications is found in Table 2.  

Rhythm Control

The section on rhythm control deals with thromboembolism prevention, electrical and pharmacological cardioversion, recommended drugs, upstream therapy, catheter ablation, and surgical maze procedures.

The authors stated that “Although an initial rate-control strategy is reasonable for many patients, several considerations favor pursuing a rhythm-control strategy.”¹ Factors in that decision include improvement in symptoms and quality of life with rhythm control, difficulty in achieving adequate rate control, younger patient age, tachycardia-mediated cardiomyopathy, first episode of AF, AF that is precipitated by an acute illness, and patient preference.¹ The document seems to promote early intervention with a rhythm-control strategy. 

Thromboembolism prevention within the rhythm-control approach includes the dictum that patients with AF or atrial flutter of 48-hour duration or longer, or with unknown duration, should be anticoagulated with warfarin with an INR goal of 2.0 to 3.0, for at least 3 weeks prior to and 4 weeks after cardioversion.¹

Direct-current cardioversion is recommended for AF or atrial flutter to restore sinus rhythm. The drugs flecainide, dofetilide, propafenone, and IV ibutilide are considered useful for cardioversion provided there are no drug contraindications. Amiodarone is a class IIa recommended therapy and is considered reasonable for conversion. Use of propafenone or flecainide as a “pill-in-the-pocket” for out-of-hospital conversion is a class IIa reasonable approach once this therapy has been observed to be effective in a monitored setting.

Drugs recommended to maintain sinus rhythm include dofetilide, dronedarone, flecainide, propafenone, sotalol, and amiodarone. Selection is dependent on underlying heart disease plus comorbidities. Amiodarone should be used only when other agents have failed or are contraindicated, and a thorough risk assessment should be undertaken.¹ A list of recommended rhythm control agents is found in Table 3.

The upstream therapy approach is an attempt to reduce or prevent disease progression. In the AF setting this means trying to modify the atrial substrate, thus delaying the cellular processes leading to AF. The class IIa recommendation for upstream therapy includes the use of an ACE inhibitor or angiotensin-receptor blocker (ARB) as being reasonable for primary prevention of new-onset AF in patients with HF with reduced LVEF. Class IIb (may be considered) approaches include therapy with an ACE inhibitor or ARB for primary prevention of new-onset AF in the setting of hypertension, and statin therapy for primary prevention of new-onset AF after coronary artery surgery.¹

The use of catheter ablation for management of AF is more broadly promoted in the guidelines than in previous versions. “The efficacy of radiofrequency catheter ablation for maintaining sinus rhythm is superior to current antiarrhythmic drug therapy for maintenance of sinus rhythm in selected patient populations.”¹ The guidelines promote catheter ablation for those in whom rhythm control is preferred and after one drug has failed. Class IIa recommendations state that AF catheter ablation is reasonable for “selected patients with symptomatic persistent AF refractory or intolerant to at least 1 class I or III antiarrhythmic medication. In patients with recurrent symptomatic paroxysmal AF, catheter ablation is a reasonable initial rhythm control strategy prior to therapeutic trials of antiarrhythmic drug therapy, after weighing risks and outcomes of drug and ablation therapy.”¹ These recommendations establish AF ablation as a first-line therapy in selected patients.

The recommendations for surgical maze procedures include a IIa and a IIb recommendation. The class IIa recommendation states that AF surgical ablation is reasonable for selected patients undergoing cardiac surgery for other indications, and the IIb recommendation states that stand-alone AF surgical ablation may be reasonable for patients who are highly symptomatic and have not been well managed with other therapies.¹

Final Considerations

Issues related to management of special populations are also included in the guidelines. This includes those with AF and hypertrophic cardiomyopathy, AF and acute coronary syndrome, hyperthyroidism, pulmonary disease, WPW and pre-excitation syndromes, heart failure, familial (genetic) AF, and postoperative cardiac and thoracic surgery.

The guidelines conclude with the recommendation of additional studies to look at treatment options and to determine mechanisms responsible for initiating and sustaining AF. In addition, there was a stated need for new rhythm control agents and anticoagulants. 

Summary

Atrial fibrillation continues to be the rhythm garnering more of our attention and energies than any other rhythm, a situation which will probably not change in the near future. The 2014 treatment recommendations offer a great overview of where we currently stand and guidance for how to proceed in a myriad of situations.

Reference 

1. January CT, Wann LS, Alpert JS, et al. 2014 AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation: Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the Heart Rhythm Society. J Am Coll Cardiol. 2014 Mar 28. doi: 10.1016/j.jacc.2014.03.021.